CIHM 
Microfiche 
Series 
(Monographs) 


ICIMH 

Collection  de 
microfiches 
(monographies) 


Canadian  Institute  for  Historical  Microraproductions  /  Institut  Canadian  da  microraproductions  historiquas 


Technical  and  Bibliographic  Notas/Notas  techniques  et  bibhographiques 


The  Institute  has  attempted  to  obtain  the  best 
original  copy  available  for  filming.  Features  of  this 
copy  which  may  be  bibliographically  unique, 
which  may  alter  any  of  the  images  In  the 
reproduction,  or  which  may  significantly  change 
the  usual  method  of  filming,  are  checked  below. 


L'Institut  a  microfilm*  la  mailleur  eaemplaire 
qu'il  lui  a  ete  possible  de  se  procurer    Les  details 
da  cet  exemplaire  qui  sont  peut-^tre  uniques  du 
point  de  vue  bibliographique.  qui  peuvent  modifier 
une  image  reproduite.  ou  qui  peuvent  eaiger  une 
modification  dans  la  mAthode  normale  de  filmage 
sont  indiquAs  ci-dessous. 


D 


Coloured  covers/ 
Couverture  de  coulaur 


I      I    Covers  damaged/ 


Couverture  andommag^e 


j      \    Covers  restored  and/or  laminated/ 
I I    Couverture  reataurAe  et/ou  pellicul^e 

□    Cover  title  missing/ 
Le  titre  de  couverture  manque 


□    Coloured  maps/ 
Cartes  gAographiques  en  coulaur 


D 


71 


Coloured  ink  (i.e.  other  than  blue  or  black)/ 
Encre  da  couleur  (i.e.  autre  que  bleue  ou  noire) 


□    Coloured  plates  and/or  illustrations/ 
PIfanches  et/ou  illustrations  en  couleur 


f~7l    Bou" 
LlJ    Reli* 


Bound  with  other  material/ 
avec  d'autres  documants 


Tight  binding  may  causa  shadows  or  distortion 
along  interior  margin/ 

Lareliure  serree  peut  causer  de  I'ombre  ou  de  la 
distorsion  le  long  de  la  marge  interieure 

Blank  leaves  added  during  restoration  may 
appear  within  the  text.  Whenever  possible,  these 
have  been  omitted  from  filming/ 
II  se  peut  que  certaines  pages  blanches  ajoutAes 
lors  dune  restauration  apparaissent  dans  le  texte. 
mais.  lorsque  cela  Atait  possible,  ces  pages  n'ont 
pas  M  fitmAes. 


D 

0 

n 

n 
n 

D 
D 
D 

n 


Coloured  pages/ 
Pages  de  couleur 

Pages  damaged/ 
Pages  endommagees 

Pages  restored  and/or  laminated/ 
Pages  restaurees  et/ou  pellicular 

Pages  discoloured,  stained  or  fox*    ' 
Pages  d^colorees.  tachetAes  ou  pi      t  i" 

Pages  detached/ 
Pages  detachees 

Showthrough/ 
Transparence 

Quality  of  print  varies/ 
Qualita  inAgale  de  I'impression 

Includes  supplementary  material/ 
Comprend  du  materiel  supplementaire 

Only  edition  available/ 
Seule  Edition  disponible 

Pages  wholly  or  partially  obscured  by  errata 
slips,  tissues,  etc  .  have  been  refilmed  to 
ensure  the  best  possible  image/ 
Les  pages  totalement  ou  partiellement 
obscurcies  par  un  feuillet  d'errata.  une  pelure. 
etc..  cnt  ite  flimies  A  nouveau  de  facor  a 
obtenir  la  meilleure  image  possible 


n 


Additional  comments:/ 
Commentaires  supplementaires 


This  item  is  filmed  at  the  reduction  ratio  checked  below/ 

Ce  document  est  filmA  au  taux  de  reduction  indiquA  ci-dessous. 

10X  14X  18X  22X 


26X 


30X 


/ 


12X 


16X 


20X 


24X 


28X 


32X 


Th«  copy  filmed  here  hes  been  reproduced  thenks 
to  the  generosity  of: 

Thomas  Fithar  Rar«  Book  Library, 
UnivarsHy  of  Toronto  Library 


L'exempieire  film*  fut  reproduit  grice  A  la 
ginirosit*  de: 

Thomas  Fishar  Rara  Book  Library, 
Univarsity  of  Toronto  Library 


The  images  appearing  here  are  the  best  quality 
possible  considering  the  condition  and  legibility 
of  the  original  copy  and  in  keeping  with  the 
filming  contract  specifications. 


Original  copies  in  printed  paper  covers  are  filmed 
beginning  with  the  front  coves'  and  ending  on 
the  last  page  with  a  printed  or  illustrated  impres- 
sion, or  the  back  cover  when  appropriate.  All 
other  original  copies  are  filmed  beginning  on  the. 
first  page  with  a  printed  or  illustrated  impres- 
sion, and  ending  on  the  last  page  with  a  printed 
or  illustrated  impression. 


The  last  recorded  frame  on  each  microfiche 
shall  contain  the  symbol  —^'  (meaning  "CON- 
TINUED"), or  the  symbol  V  (meaning  "END"), 
whichever  applies. 


Les  images  suivantes  ont  ttt  reproduites  avec  ie 
plus  grand  soin,  compte  tenu  de  la  condition  et 
de  la  nettet*  de  I'exemplaire  film*,  et  en 
conformity  avec  les  conditions  du  contrat  de 
filmage. 

Les  exemplaires  originaux  dont  la  couverture  en 
papier  est  imprimte  sont  filmte  en  commenpant 
par  Ie  premier  plat  et  en  termlnant  solt  par  la 
derniire  page  qui  comporte  une  empreinte 
d'impression  ou  d'iilustration,  soit  par  Ie  second 
plat,  salon  Ie  cas.  Tous  les  autres  exemplaires 
originaux  sont  filmis  en  commenpant  par  la 
premiere  page  qui  comporte  une  empreinte 
d'impression  ou  d'iilustration  ct  en  termlnant  par 
la  derniire  page  qui  comporte  une  telle 
empreinte. 

Un  des  symboles  suivants  apparattra  sur  la 
derniire  image  de  cheque  microfiche,  selon  Ie 
cas:  Ie  symbole  — »>  signifie  "A  SUIVRE".  Ie 
symbole  V  signifie  "FIN". 


Maps,  plates,  charts,  etc..  may  be  filmed  at 
different  reduction  ratios.  Those  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Les  cartes,  planches,  tableaux,  etc..  peuvent  Atre 
filmte  i  des  taux  de  reduction  diff«rents. 
Lorsque  Ie  document  est  trop  grand  pour  Atra 
reproduit  en  un  seul  clich*.  ii  est  film*  i  partir 
de  i'angle  supArieur  gauche,  de  gauche  A  droite. 
et  de  haut  en  bas.  en  prenant  la  nombre 
d'images  nicessaire.  Les  diagrammes  suivants 
illustrent  la  mAthode. 


1 

2 

3 

1 

2 

3 

4 

5 

6 

[XeprinUd  from  Science,  N.  S.,  Vol.  XXXIIL,  No.  36S,  P^u  899-900,  June  9,  wit] 


STUDIES  IN  ARTERIOSCLEROSIS 


..   .! 


■ill 


Mich  has  appearp<l  in  the  literature  in 
recent  years  upon  the  t-tiology  and  process  <if 
development  of  arteriosclerosis.  Many  ob- 
servations have  been  made  upon  the  human 
subject  and  also  in  experimental  animals,  of 
points  co-relating  certain  factors  with  the 
production  of  diseases  in  the  arterial  tree.  In 
most  instances  these  factors  have  been  care- 
fully studied  by  competent  ob«pr\'ers  and  in 
many  instances  the  results  have  been  verified 
by  others. 

The  gathering  of  facts  concerning  arterio- 
sclerosis  is   quite   simple— the   interpretation 
of  these  involves  much  difficulty.    In  carrying 
out  any  experiment  or  in  offering  reasons  for 
a  given  result,  we  are  constantly  reminded  of 
the  manifold  factors  which  enter  a  given  ex- 
periment   or    which    are    naturally    present. 
Often  our  experiment  on  animals  only  induces 
altered    conditions     which    indirectly    bring 
about  the  result  we  are  seeking.     That   the 
greatest  care  must  be  exe*ci.sed   in  drawing 
inferences    from    animal    experimentation    is 
well  illustrated  in  studies  upon  arteriosclerosis. 
Kecently  I^'  in  and  Larkin"  have  published 
the  results  of  their  experiments  on  dogs,  in 
which  by  producing  an  arterio-venous  anasto- 
mosis between  the  external  jugular  vein  and 
the  external  carotid  artery,  they  arrive  at  the 
sweeping  conclusion  that  "  arteriosclerosis  can 
not   be   artificially    induced    in    a    previously 
healthy  blood-vessel  by  u  change  in  the  blood 
pressure  alone."     To  this  ti/pe  of  conclusion 
we  must  take    xception. 

Levin   and      arkin,   experimenting   on   ten 
•logs,  joined  th<  external  carotid  artery  to  the 
•Jour.  Krprr.  Med..  1911.  XIFI.,  p.  L'4. 


external  jugular  vein.  In  two  of  these  <U.g^ 
thrombosis  occurred  close  to  the  line  of  suture 
in  the  vessels.  All  but  two  of  the  remaining 
eight  animals  received  injections  of  adrenalin 
at  varying  periods.  These  eight  dogs,  whioh 
form  the  positive  results  and  from  which  the 
above  positive  statement  respecting  arterio- 
sclerosis was  made,  were  allowed  to  live  Wi. 
•■?8,  72, 1,'j,  124  and  58  and  44  days,  respectively. 
Xo  one,  who  has  studied  diverse  patho!  ,^- 
ieal  lesions,  will  deny  that  the  distribution  .f 
various  lesions  in  organs  is  not  unifrrm  u 
the  animal  world.  Man  is  particularly  siih 
ject  to  lesions  of  the  circulatory  system-  .i 
condition  not  so  frequent  in  lower  animal-. 
Rabbits  and  horses  occasionally  suffer  froTii 
arterial  lesions — more  often  seen  in  the  oMei 
animals  and  in  certain  breeds.  Dogs  and  '>!U- 
rarely  develop  lesions  in  the  arteries,  even 
under  the  most  trying    ircumstances. 

This  varying  susceptibility  still  awaits  an 
explanation,  but  in  the  face  of  our  ignorane. 
in  the  matter,  we  must  assume  the  gre.ate-t 
care  iu  drawing  broad  conclusions  or  in  pro- 
posing far  reaching  principles.  Negative  e.\- 
perimental  results  for  the  dog  have  no  positive 
bearing  upon  experimental  facts  observed  in 
other  animals. 

Much  criticism  is  offered  against  the  use  nt 
the  rabbit  for  experiments  upon  the  circuLi 
tory  s.vstem.  The  comment  has  been  that 
spontaneous  arterial  disease  occurs  in  thi- 
animal.  And  yet  none  of  the  critics  offer  any 
suggestion  for  the  cause  of  this  spontaneou- 
lesion!  Properly  seleete.1  animals  and  con 
trolled   experiments   eiui    reduce   the  error  <•( 


SCIENCE 


2 


■  spontaneous  "  disease  to  almost  a  vanishing 
point.  The  Tery  feature,  in  the  rabbit,  of 
n  ailil.v  reactinjr  in  its  nrtrrial  tree  to  different 
iioxiP,  determines  its  usefulness  for  studyinp 
t\v  diseases  of  the  circulation. 

In  the  experiments  of  the  above-citwl  au- 
tliTs.  the  observations  were  made  upon  the 
Miious  segments  of  the  anastomosis.  Here 
although  in  only  some  of  the  animals  the  vein 
ttiii  noted  to  be  dilated,  it  is  concluded  that  an 
increased  blood  pressure  existed  in  all.  It  is 
not  at  all  clear  to  what  extent  the  blood  pres- 
sure was  increased  when  the  external  carotid 
and  external  jugular  were  united.  With  the 
fae  anastomosis  which  exists  (varying  much 
ill  individual  animals),  between  the  venous 
iliannels  of  the  neck,  it  is  possible  that  an 
increase  of  pressure  exists  for  only  a  short 
|..  riod  after  the  successful  anastomosis.' 

-.See  Carrel  and  Guthrie,  "Surg.  Oynac.  and 
(iLstet.,"  1906,  Vol.  II.;  and  Watts,  Bull.  Johim 
lluidins  Hosi).,  1907,  Vol.  XVIII. 


It  is  further  to  be  pointed  out  that  various 
observers  have  ret-orded  that  periodic  and  in- 
termittently   increased    hi 1    pressures    have 

<iuite  i»  ditTercnt  effect  iiiM)n  the  idood  vessels 
than  a  constant  and  continuous  one.  The 
[leriotlically  increased  pressure  is  found  com- 
monly in  man,  and  if  we  may  draw  any  con- 
clusions from  the  finding  of  occupation  scler- 
osis (right  radial  sclerosis  in  the  blacksmith, 
femoral  sclerosis  in  the  policeman),  it  is  that 
the  peritxlic  increase  of  pressure  leads  to  de- 
generations and  sclerosis  in  the  arteries. 

Finally,  but  of  primary  importance,  the 
results  of  observations  on  veins  can  not  be 
utilized  in  drawing  conclusions  aliout  arteries, 
as  has  been  done  by  Levin  and  Larkin. 


Oscar  Klotz 


University  or  Pittsbuboh, 
February,  1911 


I' 


